Personally I hope petty arguments about religious belief are kept firmly on earth. I would hate to see space defiled with man's incessant wish to divide along such lines. People have a right to believe what they want but I hope that the exploration of space remain a relatively secular area.

As for who will be the largest religion, i don't know, but the largest group will probably be agnostics because the chinese are likely to try and get a big footing in space.

By the way most eastern religions are technically monotheistic, and that includes hinduism.

I am counting Atheism as a religion here. I merely define religion as a belief system.

If you believe the universe is God you are Pantheist. If you believe the universe is a part of God you are panentheist.

Monotheistic religions see the Creator as of a different substance than the creature.

Pantheistic religions believe that the creature is of a less pure form of the divine substance. --->Believing in one god does not make you monotheistic if the god and the universe are parts of the same thing.

That is way the Hindu ideal is merger or simimerger with god (even if they believe that some sort of individuality is mantained.)

Please just go with my definition of Atheism as a religion, and Hinduism Buddism etc as pantheist or panentheist

It makes it easier to take the poll if we are using the same definitions.

I believe a space exodus will give rise to a whole bunch of new religions and branches of known ones. Buddhism will likely be one of the big shots, with several of its branches being quite well suited to space already. (Perfection in small movements, an ideal of Zen Buddhism, for example.) Christianity will also be big. It's an adaptive religion, and as such will likely be able to make the most of this new frontier. Judaism will not be big in space, unless the entire nation of Israel relocates to space for some reason (ask me some other time about whether or not it would be a good thing). Islam is rather static in its current incarnation, and thus will likely have trouble adapting (What way is Mecca from Mars again?:)), but in time, space expansion might call for a change in mindset. But the absolutely biggest religious memes out there will be agnosticism and atheism. Most people will have enough things on their minds without worrying about God or Gods.

Mormonism will be big in some places, just look at the number of Mormon sci fi authors.<---high birthrate

Judaism will be in space, there are many educated Jews. However, Jews don't have a high birthrate and don't try to convert people. This will limit their size.

Roman Catholicism will be in space, there are many Roman Catholics and many Educated Roman Catholics. <--- high birthrate

Pantheism will make it into space, but it will not be very organized compared to other faiths. It will be most popular in more "left wing" places and will possibly serve as a counter culture religion.

Atheism will be in space, it will large in some places. Space will attract people that "worship" technology.<---low birthrate

The mainline protestant denominations will not be as established in space as on earth--they have a lack of missionary zeal and do not appeal to the younger generations.

Reformed Protestantism will be in space, there are many educated Reformed people. <---high birthrate

Southern Baptist? It is a large denomination with missionary zeal. It will have some sort of presence in space.<---high birthrate

Scientology? Dunno. It will probably have some sort of "retreat" on the Moon.

Islam? It will be MUCH smaller in space than it is on Earth. Islamic nations will lag behind the rest of the world in space capibility. The current political climate will hurt Muslim growth in space for many reasons.